In-cell touch display device

ABSTRACT

Disclosed is an in-cell touch display device for preventing direct current DC accumulation from being caused by a DC voltage electric field despite using a high-resistance black matrix. The in-cell touch display device may include the passivation layer that covers the back transistor. The passivation layer may block a DC voltage electric field or may disperse electric charges accumulated based on the DC voltage electric field, and thus, even in a case where the high-resistance BM is used, DC accumulation is not caused by the DC voltage electric field. Accordingly, the in-cell touch display device prevents the DC accumulation from being caused by the DC voltage electric field despite using the high-resistance BM, thereby reducing adsorption of a pollution component.

CROSS-REFERENCE TO RELATED APPLICATIONS

This patent application is a continuation of U.S. patent applicationSer. No. 15/796,434 filed on Oct. 27, 2017 which claims the benefit ofRepublic of Korea Patent Application No. 10-2016-0142937 filed on Oct.31, 2016, each of which is hereby incorporated by reference in itsentirety.

BACKGROUND Field of Technology

The present disclosure relates to an in-cell touch display device.

Discussion of the Related Art

In an information-oriented society, technology relevant to the field ofdisplay devices for displaying visual information as an image or apicture is being developed. Particularly, there are touch displaydevices each including a display panel which senses a touched positionand a touch force when a user contacts a display area displaying animage or applies a force to the display area with a finger, a pen, orthe like. The touch display devices are being widely applied tosmartphones, automated teller machines (ATMs), ticket vending machines,exhibitions, etc. for immediate and mutual communication between a userand a machine.

Each touch display device includes a display panel which displays animage and senses a touch, a panel driver for driving the display panel,and a timing controller that supplies a signal for controlling the paneldriver. The panel driver includes a gate driver, which supplies a gatesignal to a plurality of pixels, and a data driver that supplies datavoltages to the pixels. The data driver includes a plurality of sourcedrive integrated circuits (ICs).

A display device where a display panel for displaying an image and atouch panel for sensing a touch are individually provided is defined asan on-cell touch display device. On the other hand, a display devicewhere a display panel for displaying an image supplies touchsensing-enabled information to a touch driver is defined as an in-celltouch display device. The in-cell touch display device does not includea separate touch panel, thereby decreasing a thickness of the touchdisplay device.

The in-cell touch display device includes elements for sensing a usertouch applied to a display area. Therefore, the in-cell touch displaydevice has a display period where an image is displayed and a touchperiod where a touch is sensed. During the touch period, the displaypanel is supplied with a common voltage Vcom for sensing a touch.

A direct current (DC) voltage electric field (DC field) based on thecommon voltage is generated in an outer area of the display area. Ablack matrix (BM) which divides the pixels in order for light emittedfrom the pixels not to be mixed with one another is provided on an uppersubstrate of the display panel. A general resin BM is a BM formed of aresin having a resistance which is 10⁶ Ω/D or less per unit length. Thegeneral resin BM is relatively low in resistance, and thus, disperseselectric charges well. Therefore, in a case using the general resin BM,a DC accumulation amount based on the DC voltage electric field issmall.

However, the general resin BM prevents a capacitance from beinggenerated between a touch electrode and a finger due to a touch by afinger or the like. A capacitance is generated between the general resinBM and a finger. Therefore, in a case where the general resin BM isapplied to the in-cell touch display device, touch performance isreduced. Therefore, among resin BMs, a high-resistance BM formed of aresin having a resistance which is 10¹⁰ Ω/D or more per unit lengthshould be used for enhancing a touch performance of the in-cell touchdisplay device.

When the DC voltage electric field is generated for a long time, thehigh resistance of the high-resistance BM makes it difficult to disperseelectric charges. For this reason, DC accumulation is caused by the DCvoltage electric field. In the in-cell touch display device includingthe high-resistance BM which is high in DC accumulation amount,adsorption of a pollution component occurs frequently.

SUMMARY

Accordingly, the present disclosure is directed to provide an in-celltouch display device that substantially obviates one or more problemsdue to limitations and disadvantages of the related art.

An aspect of the present disclosure is directed to provide an in-celltouch display device for preventing DC accumulation from being caused bya DC voltage electric field despite using a high-resistance BM.

Additional advantages and features of the disclosure will be set forthin part in the description which follows and in part will becomeapparent to those having ordinary skill in the art upon examination ofthe following or may be learned from practice of the disclosure. Theobjectives and other advantages of the disclosure may be realized andattained by the structure particularly pointed out in the writtendescription and claims hereof as well as the appended drawings.

To achieve these advantages and in accordance with the purpose of thedisclosure, as embodied and broadly described herein, provided is anin-cell touch display device including a display panel including a pixeldisplaying an image in a display period and a common electrode sensing atouch in a touch period, a data driver supplying a data voltage fordriving of the pixel, a common voltage compensator generating a commonvoltage for driving of the common electrode, a back transistor supplyingthe common voltage to the common electrode, and a passivation layercovering the back transistor.

It is to be understood that both the foregoing general description andthe following detailed description of the present disclosure areexemplary and explanatory and are intended to provide furtherexplanation of the disclosure as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the disclosure and are incorporated in and constitute apart of this application, illustrate embodiments of the disclosure andtogether with the description serve to explain the principle of thedisclosure. In the drawings:

FIG. 1 is a block diagram illustrating an in-cell touch display deviceaccording to one embodiment of the present disclosure;

FIG. 2 is a diagram illustrating in detail pixels, data lines, gatelines, a gate driver, and a data driver of a display panel of FIG. 1according to one embodiment of the present disclosure;

FIG. 3 is a diagram illustrating in detail a pixel of FIG. 2 accordingto one embodiment of the present disclosure;

FIG. 4 is a diagram illustrating common electrodes, common lines,feedback lines, a touch driver, and a common voltage compensator of thedisplay panel of FIG. 1 according to one embodiment of the presentdisclosure;

FIG. 5 is a waveform diagram illustrating touch signals and a commonvoltage supplied to common electrodes during a display period and atouch period of one frame period according to one embodiment of thepresent disclosure;

FIG. 6 is a circuit diagram illustrating the common voltage compensatorof FIG. 4 according to one embodiment of the present disclosure; and

FIG. 7 is a diagram illustrating a back transistor and a passivationlayer of a display panel according to one embodiment of the presentdisclosure.

DETAILED DESCRIPTION

Reference will now be made in detail to the exemplary embodiments of thepresent disclosure, examples of which are illustrated in theaccompanying drawings. Wherever possible, the same reference numberswill be used throughout the drawings to refer to the same or like parts.

Advantages and features of the present disclosure, and implementationmethods thereof will be clarified through the following embodimentsdescribed with reference to the accompanying drawings. The presentdisclosure may, however, be embodied in different forms and should notbe limited to the embodiments set forth herein. Rather, theseembodiments are provided so that the present disclosure is thorough andcomplete, and will fully convey the scope of the present disclosure tothose skilled in the art. Further, the present disclosure is onlydefined by scopes of claims.

A shape, a size, a ratio, an angle, and a number disclosed in thedrawings for describing embodiments of the present disclosure are merelyexamples, and thus, the present disclosure is not limited to theillustrated details. Like reference numerals refer to like elementsthroughout. In the following description, when the detailed descriptionof the relevant known function or configuration is determined tounnecessarily obscure the important point of the present disclosure, thedetailed description will be omitted.

In a case where ‘comprise’, ‘have’, and ‘include’ described in thepresent specification are used, another part may be added unless ‘only˜’is used. The terms of a singular form may include plural forms unlessreferred to the contrary.

In construing an element, the element is construed as including an errorrange although there is no explicit description.

In describing a position relationship, for example, when a positionrelation between two parts is described as ‘on˜’, ‘over˜’, ‘under˜’, and‘next˜’, one or more other parts may be disposed between the two partsunless ‘just’ or ‘direct’ is used.

In describing a time relationship, for example, when the temporal orderis described as ‘after˜’, ‘subsequent˜’, ‘next˜’, and ‘before˜’, a casewhich is not continuous may be included unless ‘just’ or ‘direct’ isused.

It will be understood that, although the terms “first”, “second”, etc.may be used herein to describe various elements, these elements shouldnot be limited by these terms. These terms are only used to distinguishone element from another. For example, a first element could be termed asecond element, and, similarly, a second element could be termed a firstelement, without departing from the scope of the present disclosure.

An X axis direction, a Y axis direction, and a Z axis direction shouldnot be construed as only a geometric relationship where a relationshiptherebetween is vertical, and may denote having a broader directionalitywithin a scope where elements of the present disclosure operatefunctionally.

The term “at least one” should be understood as including any and allcombinations of one or more of the associated listed items. For example,the meaning of “at least one of a first item, a second item, and a thirditem” denotes the combination of all items proposed from two or more ofthe first item, the second item, and the third item as well as the firstitem, the second item, or the third item.

Features of various embodiments of the present disclosure may bepartially or overall coupled to or combined with each other, and may bevariously inter-operated with each other and driven technically as thoseskilled in the art can sufficiently understand. The embodiments of thepresent disclosure may be carried out independently from each other, ormay be carried out together in co-dependent relationship.

Hereinafter, exemplary embodiments of the present disclosure will bedescribed in detail with reference to the accompanying drawings.

FIG. 1 is a block diagram illustrating an in-cell touch display deviceaccording to an embodiment of the present disclosure. FIG. 2 is anexemplary diagram illustrating in detail pixels P, data lines D1 to Dm,gate lines G1 to Gn, a gate driver 20, and a data driver 30 of a displaypanel 10 of FIG. 1. FIG. 3 is an exemplary diagram illustrating indetail each of the pixels P of FIG. 2. Hereinafter, an example where thein-cell touch display device according to an embodiment of the presentdisclosure is a liquid crystal display (LCD) device will be described.

The in-cell touch display device according to an embodiment of thepresent disclosure may include a display panel 10, a gate driver 20, adata driver 30, a timing controller (T-con) 40, a main processor 50, atouch driver 60, and a common voltage compensator 70.

The display panel 10 may include an upper substrate, a lower substrate,and a liquid crystal layer 13 disposed between the upper substrate andthe lower substrate. A plurality of data lines D1 to Dm (where m is apositive integer equal to or more than two), a plurality of gate linesG1 to Gn (where n is a positive integer greater than or equal to two), aplurality of common lines C1 to Cp (where p is a positive integergreater than or equal to two), and a plurality of feedback lines FL maybe provided on the lower substrate of the display panel 10. The datalines D1 to Dm, the common lines C1 to Cp, and the feedback lines FL mayintersect the gate lines G1 to Gn.

The pixels P, as illustrated in FIG. 2, may be respectively provided inintersection portions of the data lines D1 to Dm and the gate lines G1to Gn. Each of the pixels P may be connected to a data line and a gateline corresponding thereto. Each of the pixels P, as illustrated in FIG.3, may include a transistor T, a pixel electrode 11, and a storagecapacitor Cst. The transistor T may be turned on by a gate signal of akth (where k is a positive integer satisfying 1≤k≤n) gate line Gk andmay supply a data voltage of a jth (where j is a positive integersatisfying 1≤j≤m) data line Dj to the pixel electrode 11.

A common electrode 12 may be supplied with a common voltage through oneof the common lines C1 to Cp. Therefore, each of the pixels P may drivea liquid crystal of the liquid crystal layer 13 based on a potentialdifference between the data voltage supplied to the pixel electrode 11and the common voltage supplied to the common electrode 12, therebycontrolling a transmittance of light irradiated from a backlight unit.As a result, the pixels P may display an image. The storage capacitorCst may be provided between the pixel electrode 11 and the commonelectrode 12 and may maintain a constant voltage difference between thepixel electrode 11 and the common electrode 12.

The feedback lines FL may be grouped into one line and may be connectedto the common voltage compensator 70.

A color filter (CF) and a black matrix (BM), which divide the pixels Pin order for light emitted from the pixels P to not to be mixed with oneanother, may be provided on the upper substrate of the display panel 10.However, in a case where the display panel 10 is provided in a colorfilter on thin film transistor (TFT) (COT) structure, the BM and the CFmay be provided on the lower substrate of the display panel 10.

A polarizer may be attached on each of the upper substrate and the lowersubstrate of the display panel 10, and an alignment layer for adjustinga pre-tilt angle of the liquid crystal may be provided on each of theupper substrate and the lower substrate. A column spacer for maintaininga cell gap of a liquid crystal cell may be provided between the uppersubstrate and the lower substrate of the display panel 10.

The backlight unit may be disposed under a bottom of the lower substrateof the display panel 10. The backlight unit may be implemented as anedge type or direct type backlight unit and may irradiate light onto thedisplay panel 10.

The gate driver 20 may generate gate signals according to a gate drivercontrol signal GCS supplied from the timing controller 40 during adisplay period DP. The gate driver 20 may supply the gate signals to thegate lines G1 to Gn in a predetermined order during the display periodDP. The predetermined order may be a sequential order.

The data driver 30 may be supplied with digital video data DATA and adata driver control signal DCS from the timing controller 40 during thedisplay period DP. The data driver 30 may convert the digital video dataDATA into analog data voltages according to the data driver controlsignal DCS during the display period DP. The data driver 30 may supplythe data voltages to the data lines D1 to Dm during the display periodDP.

The timing controller 40 may receive the digital video data DATA andtiming signals from a main processor 50. The timing signals may includea vertical synchronization signal (Vsync), a horizontal synchronizationsignal (Hsync), a data enable signal (DE), a dot clock (DCLK), etc. Thevertical synchronization signal may be a signal that defines one frameperiod. The horizontal synchronization signal may be a signal thatdefines one horizontal period where data voltages are respectivelysupplied to pixels of one horizontal line of the display panel 10. Thepixels of the one horizontal line may be connected to the same gateline. The data enable signal may be a signal that defines a period wherevalid digital video data is supplied. The dot clock may be a signalwhich is repeated at a certain short period.

The timing controller 40 may divisionally operate the in-cell touchdisplay device according to an embodiment of the present disclosure in adisplay mode during the display period DP and operate the in-cell touchdisplay device in a touch mode during a touch period TP. The timingcontroller 40 may generate a mode signal MODE for differentiating thedisplay mode and the touch mode. In this case, the timing controller 40may output the mode signal MODE having a first logic level voltageduring the display period DP and output the mode signal MODE having asecond logic level voltage during the touch period TP.

The timing controller 40 may generate the gate driver control signal GCSfor controlling an operation timing of the gate driver 20 and the datadriver control signal DCS for controlling an operation timing of thedata driver 30, based on the timing signals. The timing controller 40may generate a touch control signal TCS for controlling an operationtiming of the touch driver 60. During the display period DP, the timingcontroller 40 may output the gate driver control signal GCS to the gatedriver 20 and may output the digital video data DATA and the data drivercontrol signal DCS to the data driver 30. The timing controller 40 mayoutput the touch control signal TCS and the mode signal MODE to thetouch driver 60. The timing controller 40 may output the mode signalMODE to the common voltage compensator 70.

The main processor 50 may be implemented with a central processing unit(CPU) of one of a navigation system, a set-top box, a DVD player, aBlu-ray player, a personal computer (PC), a personal movies system, abroadcast receiver, a smartphone, a tablet PC, and a mobile terminal, ahost processor, an application processor, or a graphic processing unit(GPU). The main processor 50 may convert the digital video data DATAinto a format suitable to be displayed on the display panel 10 and maytransmit data, obtained through the conversion, to the timing controller40.

The main processor 50 may receive touch coordinate data CD from thetouch driver 60. The main processor 50 may execute an applicationprogram associated with coordinates at which a touch is performed by auser, based on the touch coordinate data CD. The main processor 50 maytransmit the digital video data DATA and the timing signals to thetiming controller 40, based on the executed program.

FIG. 4 is an exemplary diagram illustrating the common electrodes 12,the common lines C1 to Cp, the feedback lines FL, the touch driver 60,and the common voltage compensator 70 of the display panel 10 of FIG. 1.A plurality of common electrodes 12 may be provided in the display panel10. Each of the common electrodes 12 may be connected to onecorresponding common line of the common lines C1 to Cp. Each of thecommon lines may connect a corresponding common electrode 12 to thetouch driver 60.

The feedback lines FL may be disposed between two adjacent common lines.In FIG. 4, it is illustrated that two feedback lines are disposedbetween two adjacent common lines, but the present embodiment is notlimited thereto.

The touch driver 60 may receive the touch control signal TCS and themode signal MODE from the timing controller 40. The touch driver 60 mayreceive the common voltage Vcom from the common voltage compensator 70.

The touch driver 60 may divisionally operate in the display period DPand the touch period TP according to the mode signal MODE. During thetouch period TP, the touch driver 60 may generate touch signals TS1 toTSp according to the touch control signal TCS.

The touch driver 60 may supply the touch signals TS1 to TSp to thecommon lines C1 to Cp in a predetermined order. When the predeterminedorder is a sequential order, the touch driver 60 may sequentially supplyfirst to pth touch signals TS1 to TSp to first to pth common lines C1 toCp.

The touch driver 60 may receive touch sensing signals based on the touchsignals TS1 to TSp from the common electrodes 12. The touch driver 60may perform an arithmetic operation on the touch sensing signals byusing a certain algorithm to calculate touch coordinates at which atouch is made. The touch driver 60 may supply the touch coordinate dataCD including the touch coordinates to the main processor 50. In thiscase, the main processor 50 may execute an application programassociated with coordinates at which the touch is made by a user, basedon the touch coordinate data CD and may transmit the digital video dataDATA and the timing signals to the timing controller 40, based on theexecuted program.

The common voltage compensator 70 may receive a reference common voltageVcom_REF through a reference common voltage line from a power supplysource, receive the mode signal MODE from the timing controller 40, andreceive the common voltage variation amounts of the common electrodes 12through the feedback lines FL. The common voltage compensator 70 maydivisionally operate in the display period DP and the touch period TPaccording to the mode signal MODE. Since the touch signals TS1 to TSpare supplied to the common electrodes 12 during the touch period TP, thecommon voltage compensator 70 may compensate for the common voltage Vcomaccording to the voltage variation amounts of the feedback lines FLduring only the display period DP. In detail, the common voltagecompensator 70 may inversely amplify the common voltage variationamounts reflected in the feedback lines FL with respect to a level ofthe reference common voltage Vcom_REF, thereby outputting a commonvoltage obtained by compensating for the common voltage variation amountaffected by unspecified noise occurring in the display panel 10.

FIG. 5 is a waveform diagram showing touch signals TS1 to TSp and acommon voltage Vcom supplied to common electrodes during a displayperiod DP and a touch period TP of one frame period (1 frame period). Inorder to perform all of an image display operation and a touch sensingoperation, the in-cell touch display device according to an embodimentof the present disclosure may temporally divide and drive the displayperiod DP and the touch period TP. The timing controller 40 may operatethe in-cell touch display device according to an embodiment of thepresent disclosure in the display mode during the display period DP ofthe one frame period and may operate the in-cell touch display device inthe touch mode during the touch period TP.

The touch driver 60 may supply the common voltage Vcom to the commonelectrodes 12 through the common lines C1 to Cp during the displayperiod DP. During the touch period TP, the touch driver 60 may supplythe touch signals TS1 to TSp to the common electrodes 12 through thecommon lines C1 to Cp. The common electrodes 12 may be supplied with thecommon voltage Vcom through the common lines C1 to Cp from the touchdriver 60 during the display period DP and may be supplied with thetouch signals TS1 to TSp during the touch period TP.

In FIG. 5, the one frame period is shown as including one display periodDP and one touch period TP, but is not limited thereto. In otherembodiments, the one frame period may include a plurality of displayperiods DP and a plurality of touch periods TP. The touch signals TS1 toTSp may include a plurality of pulses. Also, in FIG. 5, the touchsignals TS1 to TSp are described as having a voltage which has a levelhigher than that of the common voltage Vcom, but are not limitedthereto.

FIG. 6 is a circuit diagram illustrating in detail an example of thecommon voltage compensator 70 of FIG. 4. The common voltage compensator70 may include first and second input terminals IN1 and IN2, an outputterminal OUT, a capacitor C, and an inverting amplification unit 600.However, the common voltage compensator 70 according to an embodiment ofthe present disclosure is not limited to the illustration of FIG. 6. Inother embodiments, the common voltage compensator 70 may compensate forthe common voltage by using another common voltage compensation circuitwell known to those skilled in the art.

The first input terminal IN1 may be connected to the one line into whichthe feedback lines FL are grouped. That is, the common voltage variationamounts of the common electrodes 12 reflected in the feedback lines FLmay be input to the first input terminal IN1.

The second input terminal IN2 may be connected to the reference commonvoltage line through which the reference common voltage Vcom_REF issupplied. The reference common voltage Vcom_REF may be supplied to thesecond input terminal IN2. The reference common voltage Vcom_REF may bea DC voltage input from the power supply source.

The output terminal OUT may be connected to the touch driver 60. Theoutput terminal OUT may output the common voltage Vcom. The outputcommon voltage Vcom may be input to the touch driver 60.

The capacitor C may be provided between the first input terminal IN1 andthe inverting amplification unit 600. The capacitor C may supply thecommon voltage variation amount, input to the first input terminal IN1,to an inverting input terminal (−) of an operational amplifier (OP-AMP)OP of the inverting amplification unit 600.

The inverting amplification unit 600 may include the operationalamplifier (OP-AMP) OP, a first resistor R1, and a second resistor R2.The operational amplifier OP may include a non-inverting input terminal(+) which is connected to the second input terminal IN2 to receive thereference common voltage Vcom_REF which is a DC source voltage, theinverting input terminal (−) which is connected to the first inputterminal IN1 to receive a feedback voltage, and an OP-AMP outputterminal o. The first resistor R1 may be connected between the invertinginput terminal (−) of the operational amplifier OP and the first inputterminal IN1. The second resistor R2 may be connected between theinverting input terminal (−) and the OP-AMP output terminal o of theoperational amplifier OP. The inverting amplification unit 600 mayinversely compensate for the common voltage variation amount input tothe inverting input terminal (−) with respect to the level of thereference common voltage Vcom_REF input to the non-inverting inputterminal (+) of the operational amplifier OP, based on a resistanceratio of the first and second resistors R1 and R2 and may output theinversely-compensated common voltage variation amount.

As described above, the common voltage compensator 70 according to anembodiment of the present disclosure may receive the common voltagevariation amounts of the common electrodes 12 reflected in the feedbacklines FL, and thus, may compensate for the common voltage Vcom, based onall of the noise by which the common electrodes 12 are affected.

FIG. 7 is an exemplary diagram illustrating a back transistor T1 and apassivation layer 80 of a display panel according to an embodiment ofthe present disclosure.

An in-cell touch display device according to an embodiment of thepresent disclosure may include a pixel P which displays an image in adisplay period DP, a display panel 10 including a common electrode 12which senses a touch in a touch period TP, a data driver 30 thatsupplies a data voltage for driving the pixel P, a common voltagecompensator 70 that generates a common voltage Vcom for driving thecommon electrode 12, a back transistor T1 that transfers the commonvoltage Vcom to the common electrode 12, and a passivation layer 80 thatcovers the back transistor T1.

The common electrode 12 may be provided in plurality, and the in-celltouch display device according to an embodiment of the presentdisclosure may include a double feeding means that connects the commonelectrodes 12 by using the back transistor T1 during the display periodDP and supplies the common voltage 12 to the common electrodes 12. Thedouble feeding means may apply to the common voltage Vcom at both endsof common lines C1 to Cp to decrease the delay of the common voltageVcom applied to the common electrodes 12, thereby making the commonvoltage Vcom of the pixels P uniform in a whole screen of a display areaPA.

The back transistor T1 may be provided in plurality, and the backtransistors T1 may be disposed in a bezel, which is a non-display areaprovided outside the display area PA of the display panel 10.

The back transistors T1 may transfer the common voltage Vcom during thedisplay period DP. During the display period DP, the common lines C1 toCp may be short-circuited with one another. During the touch period TP,the back transistors T1 may divide the common lines C1 to Cp to allowthe common electrodes 12 to be independently driven.

The back transistors T1 may connect the common lines C1 to Cp connectedto a plurality of source drive ICs 31 included in the data driver 30.The back transistors T1 may be disposed in an area, which is opposite toan area where the source drive ICs 31 are disposed, of a non-displayarea. For example, as in FIG. 7, in a case where the source drive ICs 31are connected to a lower end of the non-display area, the backtransistor T1 may be connected to an upper end of the non-display area.However, the present embodiment is not limited thereto. In otherembodiments, the source drive ICs 31 and the back transistors T1 may berespectively disposed on the left and the right of the non-display areawith the display area PA therebetween.

The back transistors T1 may have a structure and a size which are thesame as those of each of thin film transistors (TFTs) of the pixels P.The back transistors T1 may be formed simultaneously with the TFTs ofthe pixels P. The back transistors T1 may each include a gate terminalconnected to a switching line L2, a drain terminal connected to a commonvoltage supply line L1, and a source terminal connected to the commonlines C1 to Cp.

The back transistor T1 may selectively connect the common voltage supplyline L1 to the common lines C1 to Cp in response to a voltage of theswitching line L2. Therefore, the back transistor T1 may selectivelytransfer the common voltage Vcom to the common electrodes 12 accordingto a signal of the switching line L2. Also, depending on the case, theback transistor T1 may additionally supply the common voltage Vcomthrough the common voltage supply line L1, thereby making the commonvoltage Vcom of the common electrodes 12 uniform in the display panel10.

The common voltage supply line L1 and the switching line L2 may below-resistance metal lines provided along the non-display area. Duringthe display period DP, the common voltage compensator 70 may supply thecommon voltage Vcom to the common voltage supply line L1 and may supplya gate high voltage VGH through the switching line L2 to turn on theback transistor T1. During the display period DP, the back transistor T1may supply the common voltage Vcom, transferred through the commonvoltage supply line L1, to the common lines C1 to Cp in response to thegate high voltage VGH applied through the switching line L2.

The back transistor T1 may maintain a turn-off state during the touchperiod TP. An alternating current (AC) signal having the same phase asthat of each of the touch signals TS1 to TSp may be applied to the gateterminal and the drain terminal of the back transistor T, for minimizinga parasitic capacitance with the common lines C1 to Cp.

The common voltage supply line L1 and the switching line L2 may beconnected to the common voltage compensator 70 through a flexibleprinted circuit (FPC).

A direct current (DC) voltage electric field (DC field) based on thecommon voltage is generated in an outer area of the display area. Ablack matrix (BM) which divides the pixels in order for lights emittedfrom the pixels not to be mixed with one another is provided on an uppersubstrate of the display panel. A general resin BM is a BM which isformed of a resin having a resistance which is 10⁶ Ω/D or less per unitlength. The general resin BM is relatively low in resistance, and thus,disperses electric charges well. Therefore, in a case using the generalresin BM, a DC accumulation amount based on the DC voltage electricfield is small.

However, the general resin BM prevents a capacitance from beinggenerated between a touch electrode and a finger due to a touch by afinger or the like. A capacitance is generated between the general resinBM and a finger. Therefore, in a case where the general resin BM isapplied to the in-cell touch display device, touch performance isreduced. Therefore, among resin BMs, a high-resistance BM formed of aresin having a resistance which is 10¹⁰ Ω/D or more per unit lengthshould be used for enhancing a touch performance of the in-cell touchdisplay device.

When the DC voltage electric field is generated for a long time, due toa high resistance of the high-resistance BM, it is difficult for thehigh-resistance BM to disperse electric charges, and for this reason, DCaccumulation is caused by the DC voltage electric field. In the in-celltouch display device including the high-resistance BM which is high inDC accumulation amount, adsorption of a pollution component occurs much.

The display device according to an embodiment of the present disclosuremay include the passivation layer 80 that covers the back transistor T1.The passivation layer 80 may cover the non-display area where the backtransistors T1 are provided. The passivation layer 80 may cover an areawhere the gate terminal, the drain terminal, and the source terminal ofthe back transistor T1 are provided.

The passivation layer 80 may be disposed between a lower substrate wherethe back transistors T1 are provided and an upper substrate where thehigh-resistance BM is provided. The passivation layer 80 may be disposedadjacent to the high-resistance BM.

The passivation layer 80 may be connected to a ground GND disposed inthe non-display area of the display panel 10. The ground GND may beprovided in one end of the display panel 10. The ground GND may set aground voltage of source voltages. Therefore, the passivation layer 80may maintain the ground voltage.

The passivation layer 80 may be formed of metal or low-resistance metaloxide. In a case where the passivation layer 80 is formed of metal, thepassivation layer 80 may use a low-resistance metal material which isthe same as that of each of the common voltage supply line L1 and theswitching line L2. In a case where the passivation layer 80 is formed oflow-resistance metal oxide, the passivation layer 80 may use a materialwhich is lower in resistance per unit area than that of thehigh-resistance BM.

For example, the passivation layer 80 according to an embodiment of thepresent disclosure may use a material having a resistance of 10⁶ Ω/D orless which is 10⁻⁴ times lower than a resistance per unit area of thehigh-resistance BM. Therefore, by decreasing a high resistance per unitarea of the high-resistance BM to that of the general resin BM, DCaccumulation based on a DC voltage electric field is reduced to that ofthe general resin BM.

The in-cell touch display device according to an embodiment of thepresent disclosure may include the passivation layer 80 having aresistance per unit area which is lower than that of the high-resistanceBM. When a DC voltage electric field is provided for a long time, sincethe passivation layer 80 has a resistance lower than that of thehigh-resistance BM, the passivation layer 80 can more easily disperseelectric charges than the high-resistance BM. Therefore, DC accumulationbased on the DC voltage electric field is smaller than a case where onlythe high-resistance BM is provided. Accordingly, in the in-cell touchdisplay device according to an embodiment of the present disclosure,adsorption of a pollution component occurs smaller than an in-cell touchdisplay device where only the high-resistance BM is provided.

For example, the passivation layer 80 of the in-cell touch displaydevice according to an embodiment of the present disclosure may beprovided adjacent to a BM which divides each of the pixels P in orderfor lights emitted from the pixels not to be mixed with one another. Inthis case, even in a case where the high-resistance BM is used, ifelectric charges can be accumulated into the high-resistance BM, thepassivation layer 80 may receive the accumulated electric charges.Accordingly, electric charges are prevented from being accumulated intothe high-resistance BM.

As described above, the in-cell touch display device according to theembodiments of the present disclosure may include the passivation layerthat covers the back transistor. The passivation layer according to theembodiments of the present disclosure may block a DC voltage electricfield or may disperse electric charges accumulated based on the DCvoltage electric field, and thus, even in a case where thehigh-resistance BM is used, DC accumulation is not caused by the DCvoltage electric field. Accordingly, the in-cell touch display deviceaccording to the embodiments of the present disclosure prevents the DCaccumulation from being caused by the DC voltage electric field despiteusing the high-resistance BM, thereby reducing adsorption of a pollutioncomponent.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the present disclosurewithout departing from the spirit or scope of the disclosures. Thus, itis intended that the present disclosure covers the modifications andvariations of this disclosure provided they come within the scope of theappended claims and their equivalents.

What is claimed is:
 1. A display device comprising: a display panelincluding a first substrate, a second substrate, and a liquid crystallayer disposed between the first substrate and the second substrate; apixel provided on the first substrate and in an intersection portion ofa data line and a gate line, the pixel disposed in a display area of thedisplay panel that displays an image; a common electrode provided on thefirst substrate and disposed in the display area of the display panel; aback transistor provided on the first substrate and disposed in anon-display area of the display panel, the image not displayed in thenon-display area, wherein the back transistor supplies a common voltageto the common electrode; and a passivation layer provided on the firstsubstrate and covering the back transistor to reduce electric chargesfrom being accumulated in a black matrix that is adjacent to thepassivation layer, wherein the passivation layer is disposed in thenon-display area of the display panel and is formed of a metal or alow-resistance metal oxide.
 2. The display device of claim 1, furthercomprising: a common voltage compensator generating the common voltagefor driving of the common electrode; and a data driver supplying a datavoltage for driving of the pixel.
 3. The display device of claim 2,further comprising: a common voltage supply line connecting the commonvoltage compensator to the back transistor.
 4. The display device ofclaim 3, further comprising: a switching line connecting the commonvoltage compensator to the back transistor.
 5. The display device ofclaim 4, wherein the common voltage supply line is connected to a drainterminal of the back transistor, and the switching line is connected toa gate terminal of the back transistor.
 6. The display device of claim1, wherein the passivation layer is connected to a ground disposed inthe non-display area of the display panel to disperse the electriccharges in the black matrix to the ground.
 7. The display device ofclaim 1, wherein the pixel is provided in plurality, and wherein theblack matrix is formed on the substrate and divides each of theplurality of pixels so that light emitted from each of the plurality ofpixels does not mix with one another.
 8. The display device of claim 1,wherein a resistance per unit length of the passivation layer is lessthan a resistance per unit length of the black matrix.